The purpose of this study is to determine if different reinforcement procedures (i.e., schedules) produce different patterns of long-term abstinence from methamphetamine. We anticipate that the three contingency management conditions will promote longer periods of abstinence in the year following treatment relative to the standard control group. Furthermore, we predict that the intermittent reinforcement procedures will produce longer periods of continued abstinence (i.e., long-term behavior change) in the year following treatment than the continuous reinforcement procedure. Finally, we predict that the intermittent unpredictable schedule will produce longer lasting behavior change than the intermittent predictable schedule. Methamphetamine use will be measured using urine toxicology and self-report of methamphetamine use.

Those in the continuous condition will receive a contingency management voucher each time they test negative for methamphetamine. The initial voucher value will be $2.50. Each consecutive instance of abstinence will increase the magnitude of the voucher by $1.50. Three consecutive abstinences will result in the delivery of a $10.00 bonus. Provision of a methamphetamine-positive urine sample, or failure to test, will result in a reset in the voucher magnitude back to its original level from whence the progression can begin again. All participants will provide observed urine samples three times a week (e.g., M, W, & F) for twelve weeks and will complete study-related measures one time per week.

Behavioral: contingency management voucher

participants receive vouchers for the provision of methamphetamine-negative urines. Vouchers can be redeemed for goods and services compatible with non-drug using behaviors.

Experimental: intermittent predictable schedule

Those in the intermittent predictable condition will earn a contingency management voucher when they provide three consecutive methamphetamine-negative urine tests. Participants in the intermittent predictable condition will receive $22.00 for the provision of their first three consecutive methamphetamine-negative urine samples, $35.50 for the provision of their second set of three consecutive instances of methamphetamine-negative urine samples, and so forth. There are no bonuses for consecutive instances of abstinence in the intermittent predictable condition. Provision of a methamphetamine-positive urine sample, or failure to test, will result in a reset in the voucher magnitude back to its original level from whence the progression can begin again. All participants will provide observed urine samples three times a week (e.g., M, W, & F) for twelve weeks and will complete study-related measures one time per week.

Behavioral: contingency management voucher

participants receive vouchers for the provision of methamphetamine-negative urines. Vouchers can be redeemed for goods and services compatible with non-drug using behaviors.

Experimental: intermittent unpredictable schedule

Those in the intermittent unpredictable condition will be eligible to receive a contingency management voucher on one day a week. Participants in this group will receive a voucher for $22.00 following their first 3 methamphetamine-negative urine tests. They will then be eligible to receive a voucher one day a week if all of their urine tests since the receipt of their last voucher were methamphetamine negative. They will receive a voucher for $35.50 for the provision of their second set of 3 consecutive instances of methamphetamine-negative urine samples, $49.00 for their third set of 3 consecutive instances, and so forth. The day of the week on which the voucher will be available will be randomly selected for each week and the participants will not know which day of the week they will be eligible to receive a voucher until they have provided their urine test. All participants will provide observed urine samples M, W, & F for 12 wks and complete measures 1x/wk.

Behavioral: contingency management voucher

participants receive vouchers for the provision of methamphetamine-negative urines. Vouchers can be redeemed for goods and services compatible with non-drug using behaviors.

No Intervention: standard

Participants assigned to the standard condition will not receive vouchers for the provision of clean urines. All participants will provide observed urine samples three times a week (e.g., M, W, & F) for twelve weeks and will complete study-related measures one time per week.

Detailed Description:

Briefly the four study conditions are: (1) standard treatment which consists of 16 weeks of psychosocial treatment, (2) continuous contingency management which consists of 16 weeks of psychosocial treatment with a contingency management procedure in effect during the first twelve weeks in which vouchers are made available after each provision of a methamphetamine-negative urine test, (3) intermittent predictable contingency management which consists of 16 weeks of psychosocial treatment with a contingency management procedure in effect during the first twelve weeks in which vouchers are available after the provision of every three consecutive methamphetamine-negative urine samples, and (4) intermittent unpredictable contingency management which consists of 16 weeks of psychosocial treatment with a contingency management procedure in effect during the first twelve weeks in which vouchers are available on one day each week (randomly selected after the first week) for the provision of methamphetamine-negative urine samples provided all urine samples since delivery of the last reinforcer were also methamphetamine negative.

Have a recent (past 30 days) history of suicide attempts and/or current serious suicidal intention or plan as assessed by the Beck Depression Inventory (BDI)

Have a history of violent criminal behavior or be on parole

Any other circumstances that, in the opinion of the PI, would interfere with safe study participation

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Please refer to this study by its ClinicalTrials.gov identifier: NCT00158197